Oxygen has an atomic number of 8.This means that oxygen has ____.
A)8 electrons in its outer most shell
B)8 neutrons in its nucleus
C)4 protons and 4 neutrons in its nucleus
D)8 protons in its nucleus
E)8 protons and 8 neutrons in its nucleus

Question

Quizplus · Accepted Answer

The atomic number of an element is equal to the number of protons in its nucleus. Oxygen has an atomic number of 8, which means it has 8 protons in its nucleus. Therefore, option D is the correct answer. Option A is incorrect because the number of electrons in the outermost shell is determined by the element's position in the periodic table, which is not necessarily equal to the atomic number. Option B is incorrect because the number of neutrons in the nucleus varies among isotopes of an element. Option C is incorrect because the sum of protons and neutrons in the nucleus gives the atomic mass, which is not equal to the atomic number for most elements. Option E is incorrect because it suggests that oxygen has an atomic mass of 16 (8 protons + 8 neutrons), which is only true for the most abundant isotope of oxygen.

Oxygen Has an Atomic Number of 8